I don't get it... the ISTp I know isn't very healthy at all... He does a lot of drugs and is overweight. Could someone explain how ISTps use Si? And do you think an ISTp would ever say something like this?

I am horribly out of tune with my body. I worked the entire time I had mono because I didn't know I had mono (I knew I was sick, but I didn't realize I was THAT sick) and worked for a week with whooping cough. I have always had a hard time sleeping. My eating habits are inconsistent. I often don't know that I'm hungry until I realize that I have no energy or I get a headache. I have passed out a handful of times due to dehydration and lack of the proper amount of rest. I have also had a few issues with taking too much stimulants and losing too much weight. People around me would scold me and try to warn me about the direction my health was headed, but I didn't see their point (at least not at the time). My hygiene... ummm... well, let's just say that I am mostly aware of my appearance because of professional reasons. I mean, I take much better care of myself than a lot of people do, but it's for reasons of practicality. I feel absolutely no motivation to make (or keep) my surroundings attractive. I do enjoy good food though. Sometimes I get almost obsessed with getting a certain food if I decide I want it. I also over indulge when I go out to eat or have whatever that food was the I wanted, to the point of feeling uncomfortable for the rest of the night.